Detrusor hypertrophy associated with bladder outlet obstruction can be imaged on suprapubic ultrasound, and bladder mass can be quantified from the evaluation of bladder wall thickness and bladder volume. Bladder wall hypertrophy has been found to be correlated with detrusor function. Independent studies have shown that surgical treatment of benign prostatic obstruction results in a significant decrease of bladder mass. Preliminary data suggest the possibility that medical treatment with alpha-adrenergic antagonists might also produce a reduction of bladder wall hypertrophy, although confirmation is still awaited. The development of dedicated automated ultrasound systems for the evaluation of bladder mass might result in the use of such parameters in clinical trials of treatment for benign prostatic hyperplasia and ultimately in daily urologic practice.